Process for the condensation of an allylic alcohol and a conjugated diene



May 13, 9 2 J. NICHOLS ET TAL PROCESS FOR THE CONDENSATION OF AN ALLYLICALCOHOL AND A CONJUGATED DIENE 5 Sheets-Sheet 1 Filed Dec. 50, 1950 m ww m v d E 4 M L mm 3 PM L O m M N MT m RW T N E lv a m m w. I" M F Em GGHF. o T n E S W. H M o T W w m FL M 1 000 awe v. 8 AG I. To U N 0 8 wnmE EM A REE F PTR F- h. m B 4 0 6 2 8 2 2 2 I O o o z mzohhom MOLAR RATIOOF ALLYL ALCOHOL TO GYCLOPENTADIENE FIG. 2

EFFECT OF PRESSURE ON THE AMOUNT OF OYOLALOL AND BOTTOMS FORMED MOLARRATIO 2.5/I

TEMPERATURE RESIDENCE TIME 2.5mm.

M M 0 T T T 0 B IIOO I200 700 900 I000 PRESSURE IN POUNDS PER SQUAREINCH 40 3405 2. miokhom 8 INVENTORS v.5. OE MARCH 8 \LNICHOLS ATTORNEY y13, 1952 J. NICHOLS ET AL 2,596,279

PROCESS FOR THE CONDENSATION OF AN ALLYLIC ALCOHOL AND A CONJUGATEDDIENE. Filed Dec. 30, 1950 3 Sheets-Sheet 2 FIG. 3

u TEMPERATURE OF REACTANTS Q I 220 m l- 5 EFFECT OF RESIDENCE TIME ONTHE '5 PER CENT 0F CYGLALOL AND BOTTOMS Q PRODUCED 2 a: MOLAR RATIO 2.5mz PREssuRE 800 psi Q g TEMPERATURE 275c B 5 E1 |40I 30 o :5 ,5 BOTTOMSIL 120- X zo I I I I I I I l I RESIDENCE TIME IN MINUTES INVENTORS v.5.DE MARCH! a J. NICHOLS BY ATTORNB-D INVENTORS J. NICHOLS ET AL PROCESSFOR II-IE; CONDENSATION OF AN ALLYLIC May 13, 1952 ALCOHOL AND ACONJUGATED DIENE 3 Sheets-Sheet 3 Filed Dec. 30, 1950 EENEE A :I L

V.S. DE MARCHI & J. NICHOLS ATTORNEYS.

Patented May 13, 1952 PROCESS FOR THE CONDENSATION OF AN ALLYLIC ALCOHOLAND A CONJUGATED DIENE Joseph Nichols, Bronx, and Vincent S. DeMarchi,Jamaica, N. Y., assignors to Interchemica'lCorporation, New York, N. Y.,a corporation of Ohio Application December 30, 1950, Serial No. 203,5312

4 Cla ims. 1 The present invention relates to the manufacture ofcondensationproducts andcomprises a process ,whereby condensationproducts of allylic alcohols with conjugated dienes, such ascyclopentadiene, butadiene, isoprene, etc., may

alcohol and pure cyclopentadiene were heated,

for 11 hours, to 175-1 80 C. The yield, obtainable .under the aboveconditions, amounted to only about 55 to 60 per cent of the theoretical.

This relatively ,low yield at which the 2,5-

endomethyle'ne A3 tetrahydrobenzyl alcohol is obtainedis due to theformation of large quantities of so-called bottoms the formation ofwhich is caused by side reactions taking place during the condensationprocess.

.Nowwe have discovered that it is possible to obtain ;2,5;'endomethyleneA tetrahydrobenzyl alcohol, for instance, in yields of 90 per cent andbetter, by reducing the time allowed for the condensationto afraction ofthat heretofore consideredessential, by using a large excess of theallyl alcohol and by condensing at increased,

but closely controlled temperatures and pressures in a continuouslyoperating system. We found, furthermore, that it isunnecessary, in thisinstance, to use the pure cyclopentadiene. Commercialdicyclopentadienewill serve equally well, since, under thehere disclosed conditions, thedicyclopentadiene is efiiciently cracked to the monomer whichthencondenses with the allyl alcohol.

Weobtainthese results ,by means of a continuous reaction, in feeding thereactants at a measured rate into, a coil, and in maintaining, at thesame time, a pressure within the said coil which is in excess of the'pressure equivalent of the temperature to which the material is beingheated.

, fljhe efficiency of I the formation of condensa- -v tion products ofthis= -type was ioundjto'be con- ;tingent upon the, correlation of four,interdependg ntv (factors: the ratio .of lthe reactants, the contacttime, the reaction temperature, and the pressure exerted uponthereaction mixture. To illustrate the interdependence between the yieldson the one hand andthe enumerated four variables on the other, weestablished, ior' instance, the following optima for the preparation of2,5- endomethylene A tetrahydrobenzyl alcohol: (a) Molecular ratiobetween allyl alcohol and cyclopentadiene: between 2 to 1 and 3 to 1.

(b) Residence time: betweenz fl and #10 minutes.

(0) Reaction temperature: ;250-300 C.

(d) Reaction pressure: in excess of 600 lbs. per square inch.

For a full understanding of the invention,

reference is made to the accompanying drawings,

wherein the Figs. 1,2fand-3 illustrate in former graphs the efieot ofthe said interdependent conditions upon the formation of thecondensation products in question and-Fig. 4 shows anembodiment of thecontinuously operating system.

The expression cyclalol which is employed on the drawings and in theherein following description is a term used to designatethemonomericcondensation product between equimolar partsof cyclopentadiene and.allyl alcohol (2,5-endomethylene A tetrahydrobenzyl alcohol).

Referring more particularly to the graph shown in'Fig. 1, it isapparentthat, at a givenpressure, temperature and residence timeof thereactants in the continuous system, the amount of cyclalol obtainedincreases for sometime with an increase in the molar ratio between allylalcohol and residence time and a [further increase in the ratio betweenthe two reactants, which would eliminate the advantages of,a continuoussystem and, because ,of the necessary subsequent removalof a great'jegcess'ofallyl alcohol, seriouslv i ai th ef l en Q Lill ie ee u Sincethe rate at which .dicyclopentadiene is cracked into the monomer idec'ieaseslrapidly with a reduction in the temperature, if dicyclopentadieneis used for the making of cyclalol according to the herein describedprocedure, temperatures below 250 C. are inapplicable.

About 300 C. is the upper temperature limit; there is a rapid decreasein the cyclalol yield and an untoward increase in bottoms if atemperature of 300 C. is exceeded.

The graph in Fig. 2 illustrates the changes in yield as a result ofvariations in pressure exerted upon the reaction mixture. Practically nocyclalol forms if, at the other stated reaction conditions, a pressureof less than 500 lbs. per square inch is employed. The yield increasesrapidly with pressure increases up to about 800 lbs. per square inch.and from there on remains practically constant. It is noteworthy thatthe amount of bottoms formed is extremely high at pressures below 500lbs. per square inch, but decreases rapidly to a minimum of less than 10per cent at pressures between 700 and 900 lbs. per square inch.

Fig. 3 explains the interrelationship between the per cent ofrecoverable cyclalol and the amounts of bottoms formed'during variousresidence times at a given molar ratio, pressure and-temperature of theheating medium.

The graph shows that the reaction resulting in cyclalol is a very rapidone, as indicated by the short residence time of 2.5 minutes at whichthe per cent cyclalol curve reaches its peak and that the reaction isaccompanied by the evolution of considerable amounts of heat. Moreover,the graph reveals the new and hitherto unexpected fact that, after thecyclalol formation has been substantially completed, a sharp breakoccurs in the temperature curve, indicating a change from an exothermicreaction to an endothermic process. Almost simultaneously therewith theamount of cyclalol decreases while the amount of bottoms formedincreases rapidly. Thus, the exposure of newly formed cyclalol tofurther heat and pressure causes changes resulting in the formation ofundesirable bottoms. For a maximum recovery of cyclalol the reactionmixture should be withdrawn from the enclosed system when reaching thehighest temperature. It will be obvious from the foregoing and from thestatements made in reference to Fig. 1 that, if the residence time wereto be extended to a periodof, say, 20 minutes, cyclalol of the purityand at the yield as herein disclosed could not be obtained. Aside fromthe necessity of a large increase in the molar ratio between allylalcohol and cyclopentadiene, as a result of the drastic temperaturereduction which would be required, the formation of cyclalol would falloff to a fraction of the amount obtained under the foregoing conditionswhile the amount of bottoms would be greatly increased.

In Fig. 4, 9 represents a storage tank for commercial dicyclopentadiene.This material, say a commercial grade product having 92 per centdicyclopentadiene and containing an appreciable amount of moisture, istransferred to one of the alternately operative driers or 7 it,containing a desiccant, such as anhydrous calcium sulfate, which caneasily be regenerated,

.by hot air for instance, whichis passed from preheater it through thesaid driers.

Simultaneously with feeding the dried dicyclopentadiene to the operatinglateral l2 of a twin proportioning pump i2, I2, allyl alcohol from tankI3 reaches the operating lateral I2 of the proportioning pump. This pumpfeeds, continuously and at a measured rate of speed, a mixture of thetwo materials into the coil M of the reactor l5, the said mixtureconsisting, in the present case, of two to three molar equivalents ofallyl alcohol and an amount of commercial dicyclopentadiene equal to onemolar equivalent of cyclopentadiene. The reactor comprises theaforementioned coil, preferably made from heavy steel tubing, havingdimensions adequate to permit retention of the reactants therein for therequired length of time. Said dimensions depend, aside from theimmediate reaction requirements, upon the material of the coil, its wallthickness and its properties of heat transfer. This coil is surroundedby a heating medium [6, such as a bath of oil or other suitable liquidof high boiling point from which heat is transferred into the interiorof the coil to heat the reaction mixture moving through the coil and tomaintain it close to a specified reaction temperature for at least partof the time during which it resides therein (250 to 300 C. in thepresent case).

The rate of flow and the pressure at which the reaction mixture is keptwithin the coil is controlled by a pressure regulator ii, jointly withregulating the speed and pressure of the propertioning pump. A properthrottling of this regulator creates the desired back pressure againstthe working pump (800 lbs, per square inch in the case at issue and,generally, from 600 up to 1500 lbs, per square inch), permitting, at thesame time, the discharge of the reacted material at the necessarypressure drop. The mixture consists, at this point, of the unsaturatedalcohol-diene condensation product, an excess of unreacted alcohol, someunreacted diene and a small amount of heavy bottoms (comprising higherpolymers of cyclopentadiene, some dicyclopentadiene, reaction productsof cyclalol with additional amounts of cyclopentadiene, and residuessuch as were present in the commercial grade di-- cyclopentadiene). 'Inorder to separate the con stituents of the mixture from each other, thematerial which has been discharged from the reactor, is transferred to astripper i8. Maintaining a temperature in reboiler It which is in excessof the boiling temperature of allyl alcohol (B. P. 96.6" 0.), permits todistill oil the unreacted portion of the latter. The allyl alcoholvapors are reduced to the liquid stage in con denser 2B, situated on topof the stripping column, and are recycled to the storage tank it.

If it should be desired to remove the small amounts of heavy bottomsformed during the condensation, the hot residual from the allyl alcoholstripper is transferred into a vacuum column 2!, where, by means ofreboiler 22 and the application of vacuum at 23 a temperature-vacuumbalance is maintained whereby the condensation product and any unreacteddiene is volatilized and the heavy bottoms are retained in liquid formin the reboiler, to be taken out at the end of the run. v(In the presentcase, a temperature of 149 C. is maintained at the base, to gether witha vacuum of about 27 to 28 inches).

The vapors, after having been liquified in a condenser ,2 i,'are drawn,by means of vacuum, into a fractionator 25, where the final product isfreed from any unreacted diene by means of a temperature-vacuumequilibrium (in the present case 118 C./2-3 inch mercury) in heating thereboiler 2B and applying vacuum at 27. While the final product iscollected in the reboiler from where it is taken at the end of the run,vapors of the unreacted diene are drawn from the column and, afterreduction thereof to the liquid stage in condenser 28, are carriedthrough a vacuum line 29 to a receiving tank 30, the latter beingconnected with tank 9. In order to prevent any losses through vaporswhich may be carried along toward the vacuum source, a vapor recoverycolumn 3|, having a charge of steam-regenerable, activated carbon isinserted between the receiving tank and the vacuum source 32.

Whereas, in accordance with the present disclosure, the allyl alcoholexcess is eliminated from the resulting reaction mixture, after suchremoval the product is useful for various purposes, such as for themaking of printing inks and surface coatings, without the necessity ofremoving the small amount of bottoms present. In this the hereindisclosed cyclalol differs radically from products of prior processeswhich resulted in material highly contaminated with heavy bottoms. Thefollowing will demonstrate the diiference:

(a) Maleic ester prepared from the reaction product of 2.5 mols allylalcohol and 1 mol cyclopentadiene, obtained after a residence time of2.5 minutes at 800 lbs. per square inch pressure in a continuous reactorheated to 275 C. and removing excess allyl alcohol from the reactionproduct, has a viscosity of 32 poises. The ester can be heat-bodied toany desired viscosity.

(b) Maleic ester prepared from the reaction product of 2.5 mols allylalcohol and 1 mol cyclopentadiene, obtained after heating for 6 hours inan autoclave to 150-l60 C. and removing excess allyl alcohol from thereaction product, has a viscosity of approximately 7500 poises. Theester is far too high in viscosity to be useful for the making ofprinting ink or surface coatings.

The maleic esters were prepared from maleic anhydride and a quantity ofthe reaction product suflicient to provide a five per cent excess overthe theoretically required amount of hydroxyl. The esterification wascarried out by the azeotropic method using five per cent xylene. Aftercompletion of the reaction, xylene and volatile components were removedby means of a vacuum distillation for two hours at 195 C./2 mm. ofmercury.

We claim:

1. A process for preparing a condensation product of an allylic alcoholand a conjugated diene, comprising commingling two to three molequivalents of the allylic alcohol with one mol equivalent of theconjugated diene, continuously introducing the commingled reactants intoa confined system, subjecting them to the action of heat from 250 to 300C. and a pressure within the range of 600 to 1500 lbs. per square inchwhich exceeds the pressure equivalent-created in the said system by heatalone, continuing said action of heat and pressure for a period of timesufficient to react substantially all of the conjugated diene with thesaid alcohol, continuously withdrawing reacted material from saidsystem, separating the unreacted portion of the alcohol, re-

moving high polymers of the diene which may have been formed during thereaction, and freeing the condensation product from any unreacted diene.

2. A process for preparing a condensation product of allyl alcohol andcyclopentadiene, comprising commingling two to three mol equivalents ofallyl alcohol with one mol equivalent of cyclopentadiene, continuouslyintroducing the commingled reactants into a confined system, subjectingthem to the action of heat from 250 to 300 C. and a pressure within therange of 600 to 1500 lbs. per square inch which exceeds the pressureequivalent created in the said system by heat alone, continuing saidaction of heat and pressure for a period of time suflicient toreactsubstantially all of the cyclopentadiene with allyl alcohol,continuously withdrawing reacted material from said system, andseparating the unreacted portion of the allyl alcohol.

3. A process for preparing a condensation product of allyl alcohol andcyclopentadiene,

comprising commingling two to three mol equivalents of allyl alcoholwith one mol equivalent of cyclopentadiene, continuously introducing thecommingled reactants into a confined system, subjecting them, for 2 to10 minutes, to the action of heat of about 250 to 300 C. and a pressurewithin the range of 600 to 1500 lbs. per square inch which exceeds thepressure equivalent created in the said system by heat alone,continuously withdrawing reacted material from said system, separatingthe unreacted portion of the allyl alcohol, and removing high polymersof the cyclopentadiene which may have been formed during the reaction.

4. A process for preparing a condensation product of allyl alcohol andcyclopentadiene, comprising commingling two to three mol equiva lents ofallyl alcohol with an amount of commercial grade dicyclopentadiene equalto one mol equivalent of cyclopentadiene, continuously introducing thecommingled reactants into a confined system, subjecting them to theaction of heat of about 250 C. and a pressure of about 800 lbs. persquare inch which exceeds the pressure equivalent created in the saidsystem by heat alone, continuing said action of heat and pressure for aperiod of time suflicient to react substantially all of thecyclopentadiene with allyl alcohol, continuously withdrawing reactedmaterial from said system, separating the unreacted portion of the allylalcohol, removing high polymers of the cyclopentadiene which may havebeen formed during the reaction, and freeing the condensation productfrom any unreacted dicyclopentadiene.

JOSEPH NICHOLS. VINCENT S. DE MARCHI.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,352,606 Alder et a1. July 4.1944 2,415,453 Thomas Feb. 11, 1947

1. A PROCESS FOR PREPARING A CONDENSATION PRODUCT OF AN ALLYLIC ALCOHOLAND A CONJUGATED DIENE, COMPRISING COMMINGLING TWO TO THREE MOLEQUIVALENTS OF THE ALLYLIC ALCOHOL WITH ONE MOL EQUIVALENT OF THECONJUGATED DIENE, CONTINUOUSLY INTRODUCING THE COMMINGLED REACTANTS INTOA CONFINED SYSTEM, SUBJECTING THEM TO THE ACTION OF HEAT FROM 250* TO300* C. AND A PRESSURE WITHIN THE RANGE OF 600 TO 1500 LBS. PER SQUAREINCH WHICH EXCEEDS THE PRESSURE EQUIVALENT CREATED IN THE SAID SYSTEM BYHEAT ALONE, CONTINUING SAID ACTION OF HEAT AND PRESSURE FOR A PERIOD OFTIME SUFFICIENT TO REACT SUBSTANTIALLY ALL OF THE CONJUGATED DIENE WITHTHE SAID ALCOHOL, CONTINUOUSLY WITHDRAWING REACTED MATERIAL FROM SAIDSYSTEM, SEPARATING THE UNREACTED PORTION OF THE ALCOHOL, REMOVING HIGHPOLYMERS OF THE DIENE WHICH MAY HAVE BEEN FORMED DURING THE REACTION,AND FREEING THE CONDENSATION PRODUCT FROM ANY UNREACTED DIENE.